In baking, which of the following is a main leavening agent?

Baking soda is a primary leavening agent commonly used in baking. It is a chemical compound that, when combined with an acid (such as vinegar, lemon juice, or yogurt), produces carbon dioxide gas. This gas gets trapped within the batter or dough, causing it to rise and create a light, airy texture in baked goods. The reaction between baking soda and the acid is what leads to leavening, which is essential in recipes like cakes, cookies, and quick breads.

In contrast, baking cocoa and brown sugar serve different purposes in baking. Baking cocoa adds flavor and color to chocolate products but does not contribute to leavening. Cake flour is a low-protein flour that helps produce tender cakes but is not a leavening agent itself. Therefore, their roles do not involve creating the lift that leavening agents like baking soda do.